ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Study of intermolecular interactions in the equilibrium catalytic transesterification of esters (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 672-676 
    Details
    ISSN: 1573-9171
    Keywords: IR spectra ; intermolecular interactions ; transesterification ; aliphatic alcohols ; esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The interaction of alcohols ROH with esters PhCOOR (R = Me,n-Bu,n-C7H15) in binary mixtures and in solutions in non-polar solvents (CCl4, cyclohexane) was studied over a wide temperature range by Fourier IR spectroscopy. Even with a great excess of alcohol (up to 3000-fold molar excess), two bands are observed in the region ofv(CO) vibrations. The low-frequency band, which is down-shifted by 15–20 cm−1 with respect to thev(CO) band in the absence of alcohol, corresponds to ester molecules bonded by hydrogen bonds of the C=O...HO type. The high-frequency band is up-shifted by 3–5 cm−1 with respect to the esterv(CO) band. The discreteness of the shift, which is confirmed by the appearance of an isobestic point, indicates that an H-complex of yet another type is formed between the alcohol and the ester. The analysis of the data available allows one to conclude that complex formation involves the alkoxyl oxygen atom of the ester. The enthalpies of formation were determined forn-BuOH H-bonds with the esters and with the transesterification catalysts, i.e., As(OBu)3, B(OBu)3, and Ti(OBu)4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00704000
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Study of intermolecular interactions in an equilibrium system in the catalytic transesterification of esters 3. Interaction of tetrabutyl titanate with alcohols from ir and NMR spectroscopic data (1991)
    Springer
    Russian chemical bulletin 40 (1991), S. 1767-1773 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reactions of tetrabutyltitanate (TBT) with alcohols have been studied using IR, Raman, and NMR spectroscopy. It has been shown that TBT is associated and has a centrosymmetrical structure. In nonpolar solvents (CCl4, cyclohexane) the associates do not break down on dilution. In the presence of butanol breakdown of the associates occurs accompanied by a reduction in the number, and even the disappearance, of bridging alkoxy groups.13C NMR results show that in mixtures of TBT and alcohols two types of exchange reaction take place simultaneously: between terminal and bridging alkoxy groups, and between TBT and the alcohol. In the case of n-BuOH the first type of exchange is retarded as the temperature is reduced to 283 K but the second is unaffected right down to 213 K. IR results show that alcohols form complexes with TBT in which the alcohol is bonded by a H-bond to the oxygen of the alkoxy group of the TBT and by the oxygen atom to the Ti of a second molecule of TBT. For the exchange reaction between TBT radicals and n-C7H15OH in a binary mixture of 1∶1 composition at 293 K, IR spectroscopy showed the degree of conversion in terms of alcohol to be 65% and the equilibrium constant Ke= 3.4. For MeOH in CCl4 solution the conversion amounted to around 100%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00960400
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Intermolecular interactions in the system of equilibrium catalytic transesterification of esters 2. Reaction of boron and arsenic butoxides with alcohols based on IR spectroscopic data (1991)
    Springer
    Russian chemical bulletin 40 (1991), S. 321-324 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction of alcohols ROH (R=Me, n-Bu, n-C7H15) with B(OBu)3 and As(OBu)3 in binary mixtures and in solutions in CCl4 was investigated by IR spectroscopy. B(OBu)3 forms equilibrium associates of two types with n-BuOH. Only one type of H bond is observed in a dilute solution of n-BuOH in As(OBu)3, but the donor sites in As(OBu)3 (As or O atoms) which participate in its formation were not established. The equilibrium constants of the reaction of exchange of butoxyl radicals in X(OBu)3 (X=B, As) with MeOH and n-C7H15OH were measured and at ∼20°C were, respectively, equal to 0.11 and 0.06 for BOBu 3 and 0.67 and 0.44 for AsOBu 3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00965424
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Study of intermolecular interactions in a system for equilibrium catalytic transesterification of esters. 1. Reaction of boron, titanium, and arsenic butoxides with esters according to IR fourier spectroscopic data (1990)
    Springer
    Russian chemical bulletin 39 (1990), S. 1808-1812 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract IR spectroscopy was used to study solutions of esters of PhCOOR (R=Me, Bu, C7H15, (CH2)2OBu) in B(OBu)3, Ti(OBu)4, and As(OBu)3 and in mixtures of the latter with CCl4 and hexane. It is shown that weak complexes form between the ester molecules and B(OBu)3 and Ti(OBu)4, As(OBu)3 behaves with respect to the esters as a nonpolar solvent. Intermolecular interaction of the esters with butoxides occurs at the alkoxide oxygen in the ester. A mechanism of the exchange of the alkoxyl radical in the reaction of Ti(OBu)4 with PhCOOMe is proposed on the basis of kinetic measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00958242
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Synthese und Eigenschaften von Polykondensationspolymeren auf der Grundlage asymmetrischer Ausgangsverbindungen (1980)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 31 (1980), S. 100-107 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The effect of conditions of synthesis on the chemical structure and properties of polymers from symmetric and asymmetric monomers is discussed for polyesters prepared by non-equilibrium polycondensation. Both homogeneous and heterogeneous polycondensation systems are investigated.
    Notes: An durch Nichtgleichgewichtspolykondensation dargestellten Polyestern wird der Einfluß der Synthesebedingungen auf den Aufbau und die Eigenschaften von Polymeren aus symmetrischen und asymmetrischen Ausgangsmonomeren diskutiert. Es werden homogene und heterogene Polykondensationssysteme untersucht.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1980.010310206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Different unit structure of copolymers obtained by polycondensation of asymmetric monomers (1991)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 91-95 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß der Reaktivitäten der funktionellen Gruppen von asymmetrischen und symmetrischen Monomeren sowie der Reaktionsbedingungen auf die Mikrostruktur der gebildeten Polyester wurde untersucht. Eine quantitative Abschätzung der Struktur unterschiedlicher Einheiten von durch Polykondensation asymmetrischer Monomere erhaltenen Interbipolyestern wird vorgestellt. Die Mikrostruktur der Copolymere hängt von der Reihenfolge der Einführung der Comonomere in das Reaktionssystem ab.
    Notes: The influence of the reactivities of the functional groups of asymmetric and symmetric monomers and of the reaction conditions on the microstructure of the formed polyesters has been investigated. A quantitative estimation is presented for the different unit structure of the polycondensation interbipolyesters obtained from asymmetric monomers characterized by two types of isomers. The microstructure depends on the sequence of introduction of the comonomer units into the reaction system.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1991.010420211
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of thermotropic polyesters (1984)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 35 (1984), S. 636-642 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polyester und Copolyester mit thermotropen flüssig-kristallinen Eigenschaften wurden durch acceptor-katalytische Polykondensation hergestellt. Es wird gezeigt, daß das Temperaturintervall der Mesophase von der Struktur, dem Anfangskomponenten-Verhältnis und dem Charakter ihrer Verteilung in den Makromolekülen abhängt.
    Notes: Polyesters and copolyesters having thermotropic liquid-crystalline properties were prepared by acceptor-catalytic polycondensation. It is shown that the temperature region of the mesophase depends on the structure, ratio of the initial components and their distribution in the macromolecules.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1984.010351005
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and properties of polycondensation polymers from compounds with asymmetric functional groups (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 2741-2749 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of conditions of polycondensation on the structure of polymers formed from monomers with symmetric and asymmetric functional groups by nonequilibrium polycondensation has been studied for the system with acceptor-catalytic polyesterification of β-hydroxyethyl ethers of bisphenols and terephthalic acid chloride in the presence of triethylamine. Polymers with statistical or regular arrangement of diol residues in the chain can be produced in such systems, depending on the way in which starting compounds are introduced in the reactor. A difference in the reactivity of functional groups in an asymmetric monomer is not sufficient to produce polycondensation polymers with a regular structure. Gradual introduction of the symmetric monomer is essential to yield polymers with predominant “head-to-head” (“tail-to-tail”) configurations. Some properties of the resulting polymers have been studied. Polymers with ordered residues of the asymmetric monomers in the macromolecules have higher softening temperatures and an increased tendency for crystallization than the statistic polymers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170131209
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...